The present invention relates to a blood sampling device that incorporates a lancet for piercing the skin and creates a partial vacuum to enhance recovery of a sample of blood.
Various types of blood sampling devices for drawing a blood sample from a skin puncture made by a lancet have been described. For example, U.S. Pat. No. 5,368,047 to Suzuki, et al. discloses a blood sampling device that has a lancet connected to a spring-loaded plunger that is reciprocable in a cylindrical housing between a retracted position and an extended position. The plunger has a gasket which makes sealing contact with the interior wall of the housing when the plunger is moved from its extended position to its retracted position.
In the operation of the Suzuki, et al. device, the plunger is pushed to its retracted position by the user and then placed against the skin from which the blood sample is to be drawn. Upon being released, the plunger is urged to travel from its retracted position to its extended position via a spring. When the plunger reaches its fully extended position, the lancet punctures the skin. After the skin is punctured, the plunger moves back to its retracted position, during which movement the pressure inside the housing is reduced due to the sliding engagement of the gasket against the interior wall of the housing. This reduced pressure, which is in contact with the skin puncture, enhances passage of blood from the puncture into the blood sampling device.